This invention pertains to film type magnetic transducer heads and more particularly to an improved transducer structure that enables intermediate testing.
In current film type transducer head designs, two layers of magnetic material are deposited on a substrate with an insulating layer separating the magnetically permeable layers except at a back gap to form a yoke with a closed magnetic path extending from the transducer gap at the pole tip portions. A substantially flat, modified spiral coil extends through the insulating material which separates the yoke layers and also isolates the coil convolution from the layers forming the yoke. The center pad of the coil is electrically connected by a jumper that is formed with the second layer of the yoke material. Thin film magnetic heads of this design are shown in U.S. Pat. No. 4,190,872 and 4,219,854. This design functions well, but is subject to some fabrication limitations that tend to compromise the yield of devices from the fabrication process. Principally, the device cannot be tested until the second permalloy layer is applied, at which time the testing becomes more complex, and the opportunity to rework failing coils no longer exists. The most difficult test is for shorted turns whereby the winding is effectively reduced by one convolution; that is an eight turn coil has become a seven turn coil. As the number of turns increases this problem will become progressively more difficult to detect. If it were possible to test the coil immediately after the conductor turns have been deposited and isolated, the procedure could be simplified, and it would also be possible to rework most of devices to full specification requirements rather than discarding the transducer that is then almost fully processed.